Gas turbine systems include a rotor unit mounted to rotate inside a stationary external housing and generally have a gearbox that is mounted at one end of the gas turbine engine. The gearbox is generally positioned adjacent the turbine engine and coupled in a manner to use power from the gas turbine engine to drive the gas turbine engine's accessories such as electrical generators, fluid pumps, and heat exchangers for cooling oil or heating fuel. The gearbox includes a several interlocking gears rotating on oil bearings. During operation of the gas turbine engine and the gas turbine engine's accessories, sub-synchronized vibrations can develop due to fluid-structure coupling between torsional and linear vibrations inside the rotating components of the gas turbine engine and gas turbine engine's accessories.
U.S. Patent App. Pre-Grant Publication No. 2009/0148084 to I. Komori et al. discloses a fluid dynamic bearing device equipped with a shaft member of high strength. The bearing device is disclosed as being capable of maintaining high bearing performance at low cost. The bearing device has a shaft member equipped with a shaft blank and a resin portion. The shaft blank has, as an integrated unit, a shaft part formed of a material of a higher strength than resin, and a protruding part protruding radially outwards from the shaft part. The resin portion covers at least one end surface of the protruding part of the shaft blank and faces a thrust bearing gap.
The present disclosure is directed toward overcoming one or more of the problems discovered by the inventors or that is known in the art.